Mercury-vapor apparatus.



P. H. THOMAS.

MERCURY VAPOR APPARATUS. APPLICATION FILED NOV. 1, 1913.

1 1 88,577. Patented June 27, 1916.

ATTOR V STATES PATENT ormon.

PERCY H. THOMAS, OF UPPER MONTCLAIB, NEW J'IEBSZEIY', ASSIGNOBTTO COOPIlB HEWITT ELECTRIC COMPANY, OF HOBO/KEN, NEW JERSEY, A. CORPORATION 01 NEW meant.

1,188,577. Original application med November 24,

To all whom it may concern:

specification.

V stances, however, my invention may be apvolta plied to other media than mercury.

It has been shown by Peter Cooper Hewitt, and others, for-example in'a number of patents issued to Hewitt, that current continuous in direction and at low voltage can be made to traverse an exhausted con-4 tainer having suitable electrodes therein,

provided means are applied for overcoming the natural reluctance to starting existing in such apparatus. In a device of thi characterthere is a loss of voltage and development of heat at each of the electrodes, the

and

sip'ation of conducting material at the surface of the cathode. There is also a loss of voltage suffered by the current in traversing the space between the electrodes which loss of voltage depends very particularly upon the dimensions and disposition of the exhausted space, the character of the gas or vapor therein and the pressure or density thereof. Furthermore in the operation of such a system, it is usually advantageous to use. a liquid cathode and mercury has been found a suitable material. During the operation of such a device, in view of theheat generated, the temperature of asolid electrodewill rise until, by radiation and by convection from the vapor coming in contact therewith, the rate dissipation of heat equals the rate of generation thereof. In

the-case of a liquid electrode, however, the

generation of heat will tend to raise the -temperature of the electrode but this will automatically cause an evaporization from the liquid since the liquid is in a closed space and the vapor pressure therein must be that of the saturation pressure of the vapor at I the temperature of the liqiud. On the other hand if there'is any point on the container.

In some in-.

fge loss being approximately constant,- rther there is a vaporization or dismover-vanes. APPARATUS.

towhich the vapor has access which is cooler than the, electrode at its surface, the saturatlon pressure of the vapor at this point will be less and a portion of the vapor the vapor near the liquid electrode and the pressure at the 0001 point of the container,

, causing a flow of vapor and the evaporization' of additional vapor from the liquid electrode in proportion ,to the amount withdrawn. Thus there will be a continuous evaporization and. condensation of the vapor from the liquid electrode at the cool spot in the container so long as the difference in temperature is maintained. This process will proceed very rapidly unless there be physical obstruction in the path of the moving vapor, thus impeding its progress and causing a permanent difierence in the pressure between the two points in the container. 4 I

' In a certain form of practical lamp of the type described by Hewitt, above. referred to, the apparatus is so proportioned as to keepthe pressure of the vapor relatively low, thus permitting a relative small loss of voltage in the tube and a wide distribution ofthe current flow. This condition can besecured only by maintaining the mercury cathode at or near a certain definite temperature which will :ordinarily be confined in the general neighborhood of the boiling point of water. In some other forms of lamp a higher pressureof the mercury vapor, Where mercury is the material used, is desirable. This is obtained by using a different proportion of 'parts, or a higher current, so that the temperature of the electrode will be higher than in the former type. In this class of apparatus the pressure of the mercury vapor is sufficiently high to confine the flow of current between the electrodes through a relatively narrowspace, usually to a space much smaller than the diameter of the container. In this case it is found that the temperature in the path traversed by the current may be very high. With such devices the containers have frequently been made of quartz, in a re-vitrified more or less transparent form, with the resultant advantage that higher Specification of Letters latent, Patentd Jung 27, 1916, I

1911', Serial No. 662,131. Divided and this application filed November 1,1913.- Seri'a1No.79 8,662.

.will be condensed until the pressure at this temperatures can be attained than could be conveniently secured with ordinary glass. However, it may be noted that as the current path becomes hot as a result of .the 1ncreascd pressure or density Within the container that it becomes feasible to maintain the surface of the tube much cooler than .the temperature of the vapor in the current surface largely near the current path, thus permitting a relatively large diametenof container and a relatively wide separation in location between the current path and the glass wall. I find that while the current may flow near the surface of the glass, at or near the electrodes, that the temperature of the glass i maintained within a reasonable limit nevertheless; perhaps by a dispersing of heat along the glass wall to the neighboring electrode.

My invention includes means whereby protection may be secured.

My invention further includes means for controlling the location of the current path within the container either to protect the walls of the container or to steady the current in the position for the purpose of preventing flickering.

My invention further contemplates means for controlling the distribution of mercury or other liquid in a vapor electric device so that a permanent apportioning of the mercury between the various points or the confining of the mercury at a predetermined point may be secured with the object of preventing the formation of drops of liquid which might fall upon a hot portion of the container and cause a momentary excessive pressure of vapor or other irregularities which appear to occur sometimes in various forms of vapor electric apparatus, i n the absence of protective means. I

My invention includes still other features which will be found in the drawings or in the following portion of myspecification.

I will describe the invention more particularly in the form set forth in the accompanying drawing in which Figures 1, 2 and 3 show special means for controlling the flow of current at or near one of the electrodes.

maaew the temperature, since with such increase in temperature there is a considerable increase in pressure and corresponding increase in the resistance of the tube so that the actual heat generated is increased at the same time that the cooling surface is reduced.

By disposing a large portion of the cooling surface about the light giving path I am able to secure a relatively wide space between the current path and the container penlnsula, or point, upon which the current may be confined by the cooling tube, 24-, which passes through the container just above the cathode and is open for the passage of air therethrough. I have found that the current in traversing the vapor path shuns any relatively cool surface, so that by this means I can confine the current to the above peninsula. This is accomplished by so curving the outline of the tube, 24, as to make any movement from the point at which current flow is desired to enter or leave the electrode surface bring it nearer to the relatively cool surface of this tube than the desired point of equilibrium. This is illustrated in Figs. 2 and 3 which are plan views of the device shown in the elevation in Fig. 1. In Fig. 3 the inner tube here identified as 25 does not extend through from wall to wall of the container. This form has advantages from the point of view of glass blowing.

The dumb bell shaped tube shown in Figs. 2 and 3 is well adapted to the present purpose.

In all these various figures I have indicated the general location of the current path by the area indicated by dotted lines marked 40. V

I do not limit myself to any one particular vapor pressure, for any desired pressure may be utilized within the practical limits of the apparatus, determined either by the matter of temperature, light density, eficiency, temperature or other conditions.

This application is a division of my application Serial Number 662,131, filed November 24th, 1911.

I claim as my invention:

1. A container for vapor electric apparatus including means for controlling the path of current within the vapor space, said means consisting of a dumb-bell shaped tube passing through the vapor space and located adjacent to an electrode, said tube being opened to circulation on-its interior.

2. A container for vapor electric apparatus including means for controlling the path of current within the vapor space, said means consisting of a dumb-bell shaped tube passing through the vapor space and located adjacent to an electrode, said tube being opened at both ends through itsinterior.

3. A tube for vapor electric apparatus, including means for controlling the point of entry or exit to an electrode, said means consisting of a portion of the walls of said tube disposed in an inclosing curve about the desired point of exit or entry to the electrode, said walls being cooled exteriorly, whereby any tendency of the current to move away from the selected point of exit or entry is corrected by the presence of a relatively cooled surface about the said point.

Signed at New York in the county of New York and State of New York this 30th day of October A. D. 1913.

PERCY H. THOMAS.

Witnesses:

ISABEL W. BONNER, THOS. H. BROWN. 

